Work Underway Soon On Ross Creek Reservoir Project
Work Underway Soon On Ross Creek Reservoir Dam
Refurbishment Project
Dunedin (Monday, 22 April 2013)
– Work will begin soon on the first stage of a major
project to refurbish the historic Ross Reservoir dam
embankment.
The dam has been closely monitored since
large cracks appeared in 2010. The monitoring plan to date
has included an irrigation system on the dam face and
gradual lowering of the water level to prevent further
instabilities occurring.
The refurbishment project,
which is part of a wider strategy to provide better water
security for Dunedin, will involve some bush and tree
clearance, temporary track closures and significant
construction work.
DCC Water and Waste Services Asset
Strategy Team Leader Tom Osborn says the DCC is very aware
Ross Creek is one of the city’s most popular recreational
areas.
“We will make every effort to retain as much
public access as possible during construction, but safety of
the public and people working on the site must come
first.”
Opus has the contract for the design and
construction management for the dam refurbishment. Initial
surveying has been completed for the preliminary design, but
some clearing work must be done to enable a detailed survey
and design of the new dam face to be carried out.
The
first stage of the Ross Creek Reservoir dam refurbishment
project will involve clearing about 0.5ha of bush and scrub
below the main embankment. Tenders for the clearance work
will close on 22 April and the selected contractors will
start on 6 May. Work is expected to take up to two weeks.
Tracks around the embankment, including the crest track,
will be closed during this time and there will be noise and
disturbance associated with scrub clearance between 8.00am
and 5.00pm, Monday to Friday.
After the first stage in
May is finished, there will be only minor activity on the
site until major construction starts about October. This
work is expected to last for about a year. Several of the
tracks around the embankment will be closed during this
period, but all tracks north of the crest will remain open
throughout. Notices will be put up on site to advise track
users of closures.
“We are looking at ways to
improve the connectivity of these tracks during construction
to try to minimise the impact of users of the reserve,” Mr
Osborn says.
Mr Osborn says some local road closures
or traffic redirections may be required as part of the major
construction works later in the year, but the extent of
these won’t be known until construction tenders close,
which is expected to be in August. The DCC will work closely
with affected parties to minimise disruption during this
period.
There are no listed significant trees on the
site to be cleared and staff are working closely with the
DCC Parks and Recreation team who manage the reserve. The
new dam face will need to be kept in low-level cover such as
grasses, but the remaining area will be replanted when all
work is complete.
The Ross Creek Reservoir, which was
completed in 1867, has not been used for about 20 years. The
dam is the oldest large earth dam in the country, and has
Historic Places Trust category one status, but it is in poor
condition and needs attention to ensure its ongoing safety.
As part of the work, 15,000cu m of fill will be brought in
to stabilise and extend the embankment. The DCC is working
closely with the Trust on the project.
The
refurbishment of the dam would mean the reservoir’s
existing capacity of 130,000cu m could be used once more,
with the water level in the reservoir restored to its
‘normal’ level after several years of being lowered. The
Ross Creek Reservoir dam project is a key part of an overall
strategy to ensure the city has water supply options should
there be any problems getting water from Dunedin’s main
water sources – Deep Creek and Deep Stream.
The
first part, which will happen this year, is the construction
of a pumping station between the Southern and Mount Grand
Water Treatment Plants, expected to cost $600,000.
The
next parts are the $2.1 million renewal of the Ross Creek
Reservoir dam and the construction of a $3.4 million pumping
station and pipeline between Ross Creek Reservoir and the
Mount Grand plant.
“Once these projects are
complete, water supply could be maintained to the entire
city if the Deep Creek/Deep Stream pipelines were lost, for
example through a seismic event,” Mr Osborn
says.
The Ross Creek/Mount Grand work will require the
old Ross Creek treatment plant site to remain off-limits to
the public for possibly another year after completion of the
dam embankment as it will probably be the field office and
yards for the pump station and pipeline project. The old
buildings will be used to house the new pump
station.
“It’s great to be able to improve the
resilience of the city’s water supplies by re-using
historic assets.”
The projects that make up this new
strategy are considerably cheaper than those originally
proposed and budgeted for in previous Long Term Plans. In
total, the strategy should deliver savings of up to $11.2
million between 2012 and
2022.
ends